Chukchi Sea

Chukchi Sea

(chək`chē), part of the Arctic Ocean N of the Bering Strait, between Siberia and Alaska, Wrangell Island lies to the west and the Beaufort Sea lies to the east. The sea has an approximate area of 200,000 sq mi (518,000 sq km) and is only navigable about four months of the year.

Chukchi Sea

a marginal sea of the Arctic Ocean along the coast of Asia and North America, washing the northern coast of the Chukchi Peninsula and the northwestern shores of Alaska. In the west it is connected with the East Siberian Sea through Long Strait, and in the south it is joined to the Bering Sea by the Bering Strait. Its northern boundary with the Arctic basin and its eastern boundary with the Beufort Sea (along the meridian of Point Barrow) are arbitrary and not morphologically delineated. The sea has an area of 582,000 sq km (according to some sources, 587,100 sq km), a water volume of 45,400 cu km, and an average depth of 77 m. The largest inlets are Kotzebue Sound and Koli-uchin Bay, and the major islands are Vrangel’, Geral’d, and Koli-uchin. The Amguema, Kobuk, and Noatak rivers flow into the sea. The shoreline is fairly regular, and the predominantly mountainous coast is fringed with lagoons and spits in many places.

The Chukchi Sea lies on the continental shelf. The isobaths of 10 m and 25 m come close to the continent and follow the outline of the shore. Fifty-six percent of the bottom area is less than 50 m deep, and 6 percent is more than 100 m deep. In the north depths increase to 200 m or more, reaching a maximum of 1,256 m. The shelf is cut by two submarine canyons: Geral’d at approximately 175°W long., and Barrow, which runs roughly parallel to the coast of Alaska. There are several rises in the northern part of the sea. Most of the bottom is covered by a thin layer of unconsolidated silt, sand, and gravel.

The sea’s position between Asia and North America and between two oceans, the Arctic and the Pacific, determines the special characteristics of its climate and hydrological regime. The polar night lasts more than 70 days, beginning in mid-November, and the polar day goes on for 86 days, beginning in mid-May. During the winter, northerly winds prevail over the sea; they are very steady in the south, especially in the Bering Strait. The average wind velocity is 6.2 m per sec. In summer, southerly winds predominate in the southern part of the sea, and light winds of variable direction in the north. The mean February temperature ranges from –21° to –27°C; the minimum temperature may be as low as –47°C. In July the mean temperatures are 2.5° –5.5°C, with a maximum of 25°C and a minimum of –6°C. The sea is completely covered with ice from late October or November until May or June, when the ice begins to break up. During the summer a warm current coming from the Bering Strait divides the sea’s ice pack into two large masses, the Chukchi and the Vrangel’. Navigation becomes possible in the southern part of the sea usually in the second half of July; the ice floes in Long Strait presents the greatest hazard to navigation.

The system of permanent currents and drifting ice is determined by the annual influx of about 30,000 cu km of relatively salty water carried by the Bering Sea Current through the Bering Strait. In the Chukchi Sea the current divides into three branches—the Alaskan, Geral’d, and Long currents—which flow, respectively, along the coast of Alaska, to the northwest (east of Geral’d Island), and into Long Strait. In the summer this current is warm, with a temperature of up to 12°C; in the winter the temperature does not exceed –1.8°C. In the course of a year it brings about 27 x 1015 kcal of heat, enough to melt the ice on more than one-third of the sea. The cold Chukchi Current arises along the coast of the Chukchi Peninsula in summer and continues to flow throughout the fall and winter. Moving southeastward toward the Bering Strait, the current carries water that has been freshened in the East Siberian Sea and that is cold in the summer and relatively warm in the winter (temperature of about –1.6°C). In the winter this current brings surface water and ice from the Chukchi Sea to the Bering Sea, forming what is known as the Polar Current.

The fresh-water component of the water balance has a very slight influence on the water circulation. The river runoff of the basin is about 78 cu km per year; the annual precipitation and evaporation total 275 mm and 119 mm, respectively. The low runoff (13 cm) is one of the reasons that the surface waters of the Chukchi Sea are more saline than those of the other Arctic seas, with the exception of the Barents, Greenland, and Norwegian seas. In summer the salinity in the Chukchi Sea is 30–32‰ (24–27‰ along the coast). The summer water temperature is 4°C in the west, 6°C in the central part, and 10–12°C in the south. In winter the water temperature from the surface to the bottom ranges from –1.6° to –1.8°C, and the salinity is 32.5–33.5%. The sea has regular semidiurnal tides of up to 0.9 m. Storm surges may cause the water level to rise by as much as 1.4 m generally and by up to 3 m at Point Barrow. In gale winds, wind-driven waves up to 6.5 m high develop in the ice-free parts of the sea.

The fauna of the Chukchi Sea, a mixture of Arctic and Pacific species, includes whales, seals, ringed seals, walruses, and polar bears. The most common fish are the grayling, navaga, arctic char, and polar cod. In the summer ducks, geese, gulls, and other seabirds inhabit the coast and islands.

The sea is a connecting link between the ports of the Far East, the mouths of the Siberian rivers, and the European USSR, as well as between the Pacific ports of Canada and the United States and the mouth of the Mackenzie River. The indigenous coastal population engages in reindeer herding, the hunting and breeding of fur-bearing animals, and the hunting of marine animals. The settlement of Uelen is a well-known center of walrus ivory carving.

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